Similar structures show up regularly on
fossilized feathers, hair and eyes, and in recent years, some
scientists have suspected they contained melanin, a dark pigment
found in the hair, skin and eyes of humans and animals.

This study, the first thorough chemical analysis of these
microscopic structures, opens the door to better understanding
the appearance and behavior of long-dead animals, said study
researcher Johan Lindgren of Lund University in Sweden.

The presence of melanin alone does not reveal the color an animal
displayed since other factors, such as other microscopic
features, can also determine color. However, melanin is evidence
of dark areas, such as bands on feathers, and the shapes of the
melanosomes may correspond to some basic hues, such as gray,
black or brown, according to Lindgren.

The presence of dark patches can provide
evidence of camouflage, social signaling or other clues to
the animal's behavior, he told LiveScience.

The tiny structures Lindgren and colleagues studied came from the
fossilized retina, at the back of the eye, belonging to a bony
fish found in Denmark. This is a first step, he said.

In 2008, a group of researchers led by Jakob Vinther, now a
postdoctoral student at the University of Texas at Austin,
concluded that tiny, organic structures like these, found in
fossilized features, were actually preserved cellular structures
that contain melanin, called melanosomes.

The most recent study adds to evidence that these tiny structures
were not left by bacteria, but came from the now-fossilized
animals' bodies, Vinther told LiveScience in an email.

"It clearly shows convincing evidence that the melanosomes we
have been working on for the last four years are composed of
melanin as we have argued earlier on," he wrote.

Lindgren and colleagues used a variety of techniques to analyze
the composition of the rounded, microscopic structures. They then
compared the results with those of modern melanin, films created
by bacteria and other compounds that common in sediments and have
a molecular structure similar to melanin.

While bacteria can produce melanin, the dark structures in the
retina at the back of the fossilized fish eye are located right
where one would expect to find pigment in a living animal, making
this the more likely explanation, he said.

The study is published in the May 8 issue of the journal Nature
Communications.